Patent GB-1447195-A (GB)
Title: Film cassettes
IPC: G03C3/00
Filed: 1974-10-24
Abstract: 1447195 Photographic processing POLAROID CORP 24 Oct 1974 [19 Nov 1973] 46158/74 Heading G2X [Also in Division B8] A film cassette includes an applicator for coating a strip of photographic film with a processing liquid subsequent to exposure of the film strip within the cassette, and means responsive to contact with the processing liquid during coating of the film strip for subsequently preventing the outflow of any excess processing liquid remaining in the applicator after the coating of the film strip has been completed. As shown in Figs. 1 and 2, the film strip 26 has its leader 46 attached by an aperture 48 to a takeup spool 36 and its trailer region 50 attached by an aperture 52 to a supply spool 28. In its path between the spools 28, 36, the film extends across a normally inoperative film processing station 38 and across an opening 40 for facilitating, at different times, exposure and projection. A prism 42 is provided for projection purposes. Preferably, the film carries, at least over a photographically useful length 44, an emulsion or photo-sensitive coating capable of being developed by a monobath composition. Preferably, the film is driven by a double claw pawl (not shown) engaging in sprocket holes 54 and which engages in a hole 56 to stop the advance of film in the camera and in a hole 58 to determine a film take-up or projection end point. The station 38 comprises a pre-packaged container 68 of processing fluid 73 retained in a chamber 66 and a lower chamber 70 which co-operates with a nozzle 72. The fluid 73 is retained in the container 68 by a tear tab 74 extending to an actuating assembly 84 having a hook 86 releasably latched to a post 88 and in engagement with a can member 90. A pressure pad assembly 96 is urged towards the nozzle 72 by a leaf-spring 98 and carries a slide valve 120 including a plate 122 having a piece of compressed open cell foam material 124 thereon to seal the nozzle opening when the valve 120 is moved to the right of Fig. 1. At the station 38, a J-shape sheet 142, Fig. 7, of compressed open cell cellulosic sponge material overlies the chambers 66, 70 and the container 68 and is retained by a cover plate 144 having pins 148, 150 engageable in holes 152, 154. The material 142 is impregnated with a polymer which has a finite reaction time with the fluid 73. In operation, upon insertion of the cassette into a projector (not shown), following exposure of its film, a latching-shaft (not shown) enters the cassette and depresses the cam 90 to release the assembly 84 so that the hook 86 engages one of four teeth 92 on the spool 28. The double claw (not shown) drives the film 26 slightly further forward so that a projection 60 on the film displaces an end 100 of the assembly 96 to the left of Fig. 1 to allow the spring 98 to push the assembly 96 upwardly to push the film 26 into engagement with the nozzle 72. After initiation of the film rewind, the clockwise rotation of the spool 28 tears the tab 74 from the container 68 so as to release the fluid 73 which flows past the material 142 to the nozzle 72 so that a thin layer thereof is  deposited on the film during rewind. When the material 142 is contacted by the fluid 73, the reaction between this fluid and the polymer impregnated within the sponge begins and continues for approximately 10 seconds before the material 142 is released by the polymeric bond for expansion and absorption of excess processing fluid. When the film 26 is substantially rewound, an aperture 62 therein engages an arm (130), Fig. 5 (not shown), of the valve 120 to displace this valve to the right of Fig. 1 until downwardly depending posts (114), (116), Fig. 4 (not shown), on the nozzle 72 are contacted by shoulders (not shown) on the plate 122 to locate the material 124 in sealing location beneath the nozzle 72. Remaining portions of the fluid 73 in the region of the nozzle orifice contact the material 124 which expands to form a miniscus shape seal within the nozzle orifice.